Foam rubber method



July 16, 1968 'r. TROGDON FOAM RUBBER METHOD 2 Sheets-Sheet 2 Filed Nov.10, 1966 4 v v 4/ o o 0 0 o 0 r 0 o 0 0 o o o w o 0 0 0 u 0 o o o o o 00 0 000000000 0 o o o o 0 0 o 0 0 0 0 0 0 o 0 o 0 0 0 o I o o o o a o oo a I 0 000000000 0 0 o 0 o o o o o 0 0 0 o o o o o 0 0 o o 0 0 o o o 00 0 0 o 0 o 0 0 0 0 0 0 0 a 1 000000000 0 000 00000 0 4 0 o o o 0 o 0 o0 0 AU 0 o o o o o 0 0 0 I r 0 7 2 M 2 1 00 0/ 0w 0w 0- o O 0 y 00000 0M00000 0 I o M 0 o 0 o o o o o o 0 w 0 0 0 0 o 0 o 0 o o o o o 0 o 0 0 00 0 0 0 0 o o o r 0 0 QIXAIIQOQ O O 0 0 O OO O/ 0 o l o o o o o o o 0 ao 0 0 0 0 0 a o o 0 o H 0 0 o o o 0 0 0 0 0 0 0 0 0 0 o 0 0 o o \I. o o0 o o o 0 0 o 0 o 0 0 0 o 0 o 0 7 7 O O l 0 o a 0 o 0 o o o 0 0 0 0 0 .0o o o H 0 o o 0 0 0 0 o o o 0 0 o 0 0 0 o 0 w o 0 o o o 0 0 0 0 0 o 1 0u 0 0 0 0 o w 0 XJQ O Q Q 0 O 0 8 0 0 7 0 0 o 0 o o o 0 0 1 0 0 0 0 0 00 0 o v 0 o 0 o o 0 0 0 0 0 0 o 0 0 0 0 o 0 w o RV 0 o o o 0 a o o o o 1J o 0 0 0 0 0 o o o 0 o G o o a o o o a o o l G o o o o o o o o ar/////////// INVENTOR. THOMAS TROGDON Mi t ATTORNEY United States Patent"ice 3,393,259 FOAM RUBBER METHOD Thomas Trogdon, Waynesville, N.C.,assignor to Dayco Corporation, Dayton, Ohio, a corporation of DelawareContinuation-impart of application Ser. No. 318,366, Oct. 23, 1963. Thisapplication Nov. 10, 1966, Ser. No. 600,335

7 Claims. (Cl. 264-46) ABSTRACT OF THE DISCLOSURE The method of makingfoam rubber products having segments of dissimilar densities. Dissimilarlatices are introduced into different portions of a mold cavity havingcore pins more closely spaced to create barrier rows which separate thelatices during foaming and vulcanizing.

This application is a continuation-impart of application Ser. No.318,366, filed Oct. 23, 1963, now abandoned.

This invention relates to a method for manufacturing unitary foam rubberarticles, and more particularly to such articles as mattresses, pillows,furniture cushions, automobile seat cushions, and the like.

Articles of this nature are normally manufactured by the use of metalmolds having upper and lower mold members, the lower member having acavity in which the mold is partially filled with a liquid rubber latexcomposition that is foamable; that is, has been compounded to permitfoaming. The foamed material is subsequently coagulated and vulcanizedas more fully described in United States Patent No. 2,432,353, one ofthe series of patents which describes the so-called Talalay process. Themold cavity and upper mold member contain a number of core pins whichproject into the pin cavity so that the resultant product has a numberof corings extending inwardly from both surfaces.

At the present time the above-described process utilizes a latexcomposition which is uniform so that the resultant product is uniform indensity throughout. In many instances, however, it has been founddesirable to provide a product which has dissimilar densities in variousportions thereof. While such a process and product have been known inthe past, it has only been accomplished by fabricating two dissimilarmembers and cementing them together as described, for example, in UnitedStates Patent No. 2,612,158. Such a method of fabrication has provedunsatisfactory, however, because of the extra time, expense and laborinvolved.

It is, therefore, a primary object of this invention to provide a methodfor the manufacture of cushioning members which are unitary, yet containmaterial of dissimilar density in various portions thereof.

It is a further object to provide a method for manufacturing suchproducts by inexpensive methods.

In the practice of this invention various types of molds have beenutilized in the conventional Talalay process, such as described, forexample, in United States Patent No. 2,615,202. In accordance with theprior art, molds having upper and lower members and containing core pinshave been previously utilized. Applicant has conceived the idea of usingthis apparatus for the manufacture of a product having dissimilardensities as described above, by introducing two or more latices ofdissimilar densities into various portions of the mold cavity. Becauseof the foamable nature of these latices, they will foam withinrespective portions of the mold cavity and maintain separate identitiesduring the process. In order to promote this separation of identity, theconventional apparatus is modified so that certain of the core pins inthe mold cavity are increased in number to form a barrier. This is doneby 3,393,259 Patented July 16, 1968 reducing the spacing betweenadjacent core pins in certain selected rows so that the resultant rowsserve as barriers to prevent each of the latices from flowing out of apreselected area of the cavity, while at the same time the spacing issuch that an acceptable product results. During the foaming andsubsequent vulcanizing the mating edges of the foam segments will mergeto form a unitary product. The invention will be more fully described inthe following description and accompanying drawings, in which:

FIGURE 1 is a perspective view of a typical mold used in practicing thepresent invention.

FIGURE 2 isa sectional view taken along lines 2.-2 of FIGURE 1.

FIGURE 3 is a sectional view taking along lines 33 of FIGURE 1.

FIGURES 4, 5 and 6 are sectional views similar to FIGURE 2 illustratingfurther modifications of the invention.

Referring now to the drawings, FIGURE 1. illustrates a mold consistingof a lower mold member 11 and an upper mold member 12. The lower moldmember 11 has four sides 28, 29, 30 and 31 and a base 32, all defining acavity 33. On the upper surface of the base are mounted core pins14. Theupper mold member 12 also has core pins '13 mounted therein, adapted toclose on member 11 in order to provide a completely enclosed mold duringfabrication. As better shown in FIGURE 2, the core pins 14 in the moldcavity are aligned in rows in which the pins have an equal spacing. Anexception to this spacing pattern, however, is found in the rowsdesignated as 15, 16, 22 and 23, forming rows which are parallel to theperiphery of the mold cavity. In these rows, which are designated asbarrier rows, the spacing of the pins is reduced to approximately halfof the spacing of the other rows.

When it is desired to fabricate the finished product, nozzles are usedto introduce liquid rubber latex into the various portions of the mold.The latex, as indicated above, is a foamable one which may be formulatedin accordance with the description in the above-mentioned Patent No.2,432,353. The density of the final product may be controlled bycontrolling the amount of latex which is poured into a given portion ofthe mold, the density increasing as a greater amount of latex is added.It is also possible to accomplish this by varying the amount of air inthe latex, either by mechanical agitation or by variation of the yeastor peroxide compounded therein. Increasing the amount of entrapped airresults in a reduction of density and a softer foam. As shown in FIGURE3, nozzle 24 provides a latex 26 of a density (preferably about 0.35gram per cubic centimeter) which provides a comparatively firm foammember. This latex is introduced into the outer peripheral portion ofthe mold cavity. The nozzle 25 introduces latex 27 into the remainingportion of the mold cavity; this latex has a density of approximately0.2 gram per cubic centimeter and provides a comparatively soft foammaterial. The latices are separated by the barrier rows and are thuskept from flowing together and becoming intermingled. At the same time,however, there is sufiicient space between the pins in these barrier.rows so that the completed foam product will not be cut into aplurality of segments by the pins. As soon as the latices have beenintroduced, the top of the mold is closed and the subsequent process asdescribed in the aforesaid Patent No. 2,432,353 will take place. Thelatices will foam into the typical stereoreticulate structure whilemaintaining distinct identities. As further processing continues thefoaming is completed and the finished product is subsequentlyvulcanized. During this time the barrier rows will tend to keep thebodies 3 r. of latex apart and yet the edges of the adjacent bodies willbe permitted to contact each other so that a unitary product willresult. The resultant product will then be a molded foam article havinga comparatively firm peripheral edge and yet completely unitary.

A modified form of the invention is illustrated in FIG- URE-4 in whichthe barrier row 17 extends along the longitudinal center line of themold cavity instead of the peripheral configuration of FIGURES l and 2.The mold construction of FIGURE 4 is otherwise like that of FIG: URE 1,but the barrier row 17 will be the only one having the reduced core pinspacing. By means of this mold configuration the cavity. is eliectivelydivided into two halves so that the introduction of latices of difierentdensities into these two halves will permit the formation of a foamrubber article having dissimilar densities in the two halves, yet whichis a unitary product. This process Will occur exactly in the same manneras that described above with reference to the peripheral configuration.

FIGURE illustrates a further form of the invention in which the moldcavity contains barrier rows 18 and 19 which have the reduced spacingdescribed above. In this case the barrier rows are located transverselyof the mold cavity to define the central and end portions which areapproximately equal. Of course, it is understood that the area of thesesegments may be any dimension in accordance with the desired endproduct; for example, the end portions may be smaller than the centralportion. When manufacturing finished products utilizing this pattern,one latex may-be introduced into the central portion and another latexinto the two end portions; or three dissimilar latices may be used. Inany case, the same process as described above with reference to theother configurations will take place.

FIGURE 6 illustrates still another form of the invention in whichbarrier rows 20 and 21 are located longitudinally of the mold cavity toprovide three longitudinal segments. The processing takes place exactlyas described above, and latex of one density may be introduced into thecentral longitudinal portion, while latex of a dissimilar density may beintroduced into the two outer longitudinal portions, or three latices ofdissimilar density may be used.

Although certain forms of the invention have been described, it shouldbe noted that other modifications are contemplated as falling within thescope of the invention. The basic principle of the invention, however,has been described in which barrier rows of core pins are located in themold cavity to create segments of a foam material which will merge attheir mating edges to create a unitary member.

What is claimed is:

1. The method of manufacturing molded unitary toam rubber articles in amold cavity having core pins mounted therein, comprising the steps ofproviding barrier rows having pins spaced more closely than in theremaining rows to separate said cavity into difierent portions,introducing foamable rubber latex into one portion of said cavity,introducing foamable rubber latex of a different density into theremaining portion of said cavityf rnaintaining separate identity of saidlatices by means, of said barrier rows, and foaming and vulcanizingsaid'latices to form a unitary member while maintaining separateidentity of the resulting foamed segments. I

2. The method of claim 1 including the steps of locating a barrier rowalong the longitudinal Center line of said mold cavity and introducingone of said latices into each portion of said cavity defined by saidrow.

3. The method of claim 1 including the steps of locating barn'er rowsparallel to the periphery of said mold cavity, introducing one of saidlatices into the outer peripheral portion of said cavity defined by saidrows, and introducing the other of said latices into the remainingportion of said cavity.

4.'The method of claim 3 in which the latex said peripheral portion hasa greater density than the latex in the remaining portion.

5. The method of claim 1 including the steps of locat ing barrier rowstransversely of said mold cavity to define central and end portionstherein, introducing one of said latices into said central portion, andintroducing the other of said latices into said end portions.

6. The method of claim 1 in which the latex in said central portion hasa greater density than the latex in said end portions.

7. The method of claim 1 including the step of locating at least onebarrier row longitudinally of said mold cavity to define at least twolongitudinal portions therein.

References Cited UNITED STATES PATENTS 2,150,287 3/1939 Minor 264-462,432,353 12/1947 Talalay 264-54 XR 3,328,847 7/1967 Trogdon 264-50 XRFOREIGN PATENTS 373,781 6/1932 Great Britain.

JAMES A. SEIDLECK, Primary Examiner.

PHILIP E. ANDERSON, Examiner.

